This invention relates generally to the hardening of ceramic-surfaced articles. More particularly, it relates to a method for hardening ceramic-surfaced tools and machine components and to the hardened articles so produced.
Industry's continuing search for harder and longer-lived tools and machine components has led to the development of ceramic-surfaced drills, bearings, valve seats, saws, linings, and the like. Although such articles have been in widespread use for many years, it has long been evident that a simple and practical method for increasing the hardness properties of such articles would be a valuable and important advance in the art. Ceramic-surfaced tools and machine elements are composed throughout of the ceramic or are provided with bonded surface coatings of the same.
In the past, ion implantation has been used to alter to the electrical properties of ceramic semiconducting materials--e.g., Si and GaAs--and to alter the wear and oxidation properties of metals. The state of the art is described in the following reference: J. K. Hirvonen, ed., "Ion Implantation", Vol. 18, Treatise on Materials Science and Technology, Academic Press, New York, (1980).
The following reference discusses damage effects produced in .alpha.-Al.sub.2 O.sub.3 single crystals by the implantation of Pb.sup.+ ions: A. V. Drigo et al., Lattice Disorder in Implanted Insulators: Pb Implantation in .alpha.-Al.sub.2 O.sub.3, Radiation Effects, 33, 161-171 (1977).
It is an object of this invention to provide a new method for producing ceramic-surfaced tools and machine components characterized by increased hardness and/or toughness to fracture.
It is another object to provide ceramic-surfaced tools and machine components characterized by increased microhardness, wear-resistance, and/or toughness to fracture.
It is another object to provide a method for hardening ceramic rubbing surfaces, such as a work surface of a frictional clutch.
Other object will be made apparent hereinafter.